Q. If one root of the equation $x^{2} - \lambda x + 12 = 0\ is\ even\ prime\ while\ x^{2} + \lambda x + \mu = 0$ has equal roots, then $\mu$ is

A) 8
B) 16
C) 24
D) 32
Explanation

(b)
We know that only even prime is 2, then
$(2)^{2} - \lambda(2) + 12 = 0\ \Rightarrow \ \lambda = 8$ …(i)
and $x^{2} + \lambda x + \mu = 0$ has equal roots.
$\therefore\ \lambda^{2} - 4\mu = 0$ or $(8)^{2} - 4\mu = 0$ [ from Eq. (i)]
$\therefore\ \mu = 16$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.